The present invention relates to document-handling systems and, more particularly, to document-handling systems in which information must be imaged from a document that is transported automatically through a machine.
In document scanning devices, such as character recognition systems or copiers, a good deal of time and effort can be wasted if it is necessary to locate each document by hand in a position which will allow the information on the document to be read or copied. Either system usually requires segments of a document to be optically scanned. In order to preserve the information carried by the document, its movement through the scanning section of the machine must be relatively slow. However, the movement through other parts of the machine may be relatively fast. Thus, there is a tendency for paper to build up into a stack in the machine in those sections prior to a slow operation; e.g. scanning. In order to accomplish this, some form of buffer must be provided to accommodate the stack of documents.
In some prior art systems stacks of documents at the input to the scanning section are stacked in an automatic elevator. Such a system is disclosed in U.S. Pat. No. 4,171,129 of Daley et al., which is assigned to the assignee of the present invention. With the arrangement disclosed in that patent, a horizontal stack of documents is manually loaded onto an elevator. The elevator positions the topmost document under a feed roller which moves it into a pair of paper-separating rollers. The top roller of the pair moves in the same direction as the feed roller, but the other roller moves in the opposite direction so as to push back into the stack any documents pulled along with the topmost document. Once the document has passed through the separating rollers, it is aligned and scanned at slow speed. Then it is rapidly moved into a storage bin.
The elevator of the above-identified Daley et al. patent is useful as an input to an automatic document tranport, but it could not be used in the middle of such a system in which documents were automatically moved at a high speed through initial operations and then automatically stacked and fed at a slower speed into a subsequent operation. In addition, the document elevator in the prior patent is adapted to handle a stack of documents lying flat, i.e. horizontal, and could not automatically stack vertically-arranged documents, i.e. documents being transported on one edge.